1. Field of the Invention
The present invention relates to the protection of the confidentiality of data stored on a CD-ROM.
2. Discussion of the Background
The only possibility for safeguarding the confidentiality of data stored on a CD-ROM is encryption. However, this protection is not actually satisfactory other than to the extent that the decryption key remains inaccessible from the user, this not being the case when the decryption key is stored on the CD-ROM or provided to the user in some other way. Moreover, there is often a considerable risk of the decryption key being pirated at the level of the electronic decryption circuit itself, whether it be located in the CD-ROM drive or downstream.
Various attempts have already been made to solve this problem.
In the case of cassettes or magnetic diskettes which are contained in an irremovable casing, it is known practice, through international patent application WO-A-89/12890, to equip the casing with an electronic chip provided with electrical contacts. The data are coded on the recording medium, whether this be a cassette or a magnetic diskette, and decoded by way of the electronic chip with which the casing is equipped. This kind of protection cannot be used with a CD-ROM since the latter is not presented in an irremovable casing. Furthermore, it is not entirely safe since the decoding key must be known to an authorized user who may at leisure allow other, even unauthorized, users who possess the appropriate drive to avail themselves of this key.
In the CD-ROM case, it is known practice, through German patent application DE-A-43 07 395, to code the data recorded on the CD-ROM with the aid of a key or password and to store the password in a chip card. This makes it possible, a priori, to preclude the use of the data from the CD-ROM by users who are not in possession of the chip card. However, there is still a risk of pirating because the password is not actually made secure inside the CD-ROM drive or the CD-ROM itself.
The purpose of the present invention is to remedy these various drawbacks and to ensure effective protection of the confidentiality of data stored on a CD-ROM.
Its subject is a system for the secure CD-ROM storage of data comprising a CD-ROM on which are stored data encrypted at least in part with a cryptographic algorithm having a decryption key K and a CD-ROM drive. This system for the secure storage of data is noteworthy in that it furthermore comprises:
an electronic decryption microcircuit embedded in the said CD-ROM,
means of exchanging information between the CD-ROM drive and the electronic decryption microcircuit embedded in the CD-ROM,
a chip card containing at least a part K1 of the decryption key K, any remaining part K2 of the decryption key K figuring in the electronic decryption microcircuit embedded in the CD-ROM and,
secure means of exchanging information between the chip card and the electronic microcircuit embedded in the CD-ROM.
By virtue of this system, the confidentiality of the data stored on CD-ROM is ensured by means of encryption, the decryption key of which is never accessible to the user in unenciphered form, thus to a large extent reducing the risks of fraud.
The electronic decryption microcircuit embedded in the CD-ROM is advantageously provided with an inductive or capacitive antenna making it possible to cater from outside the CD-ROM, in the absence of any contact, both for its electrical power supply and for information exchanges.
The CD-ROM drive is advantageously provided with a chip card connector and with an electronic circuit which caters, apart from for the reading of the CD-ROM, for the management of the links for exchanging information between itself, the electronic microcircuit embedded in the CD-ROM and the chip card.
The chip card is advantageously provided with a code for identifying its owner which must necessarily be delivered to him/her at the start of a session in order for the card to agree to communicate with the outside, whilst the CD-ROM drive is equipped with means for monitoring the uninterrupted presence of a chip card in its chip card connector throughout a decryption performed by the electronic microcircuit embedded in the CD-ROM.